Sensorless control of electro-mechanical flight control actuators

Abstract

Electro-mechanical flight control actuators become a viable option to replace conventional hydraulic actuators in future more electric aircraft. A rotor angle measurement is generally required for field-oriented control of the electrical machine and usually obtained from a safety-critical resolver. It contributes, however, to a rising local hardware complexity with negative impact on space allocation, weight, motor inertia, reliability and cost. This paper investigates sensorless control strategies which might substitute the resolver by an accurate estimate value. A hybrid observer is implemented that allows position control without an angle sensor at all speeds. In the high speed domain, the extended electromotive force of the permanent magnet synchronous machine is used for angle estimation, whereas in the low speed domain including standstill anisotropy properties of the motor are exploited applying the alternating injection method. The performance of the control algorithm is evaluated on an aileron actuator test rig for large civil aircraft.